Cyclophosphamide is a prodrug of a nitrogen mustard alkylating agent, in which the reactivity of the bis(2-chloroethyl)amino group is attenuated. Upon oxidation in vivo the six-membered ring opens, enhancing the reactivity of the nitrogen mustard, which then acts to cross-link DNA. Cyclophosphamide has severe and life-threatening adverse effects, including acute myeloid leukemia, bladder cancer, hemorrhagic cystitis, and permanent infertility, especially at higher doses. Ifosfamide is also a nitrogen mustard alkylating agent used in the treatment of cancer. Ifosfamide can cause encephalopathy, affects peripheral nerves, and interfere with neurological development in children.

So far, there is no commercial immunoassay kit for the detection of cyclophosphamide or ifosfamide. Additionally there are no commercially available antibodies against cyclophosphamide or ifosfamide. Therefore, there exists a need for developing immunoassays for these cytotoxic agents.